Northern Lights Now – Comet NEOWISE will be visible in the Northern Hemisphere In July and August 2020. The best viewing times will be just before dawn between July 1st and July 15th, then in the evenings starting around July 12 and continuing in to August. In the mornings, the comet and it’s tail can be seen in the Northeast sky about 80 minutes before sunrise. In the evenings look in the Northwest sky, about 80 minutes after sunset. The comet won’t be visible in the Southern Hemisphere.
The comet is visible low on the horizon. This means viewers need an unobstructed view with no trees, buildings, mountains. A higher altitude will also give a better viewing. At the best viewing times there will also still be light in the sky from sunrise or sunset so the darker a place the better. Getting out of the city, climbing a mountain and getting a clear horizon will be increase chances of seeing the comet.
How Bright Will the comet be?
Predicting how bright this comet will be is tough and has defied and surpassed expectations thus far. The best short advice is to get out and see the comet soon because it may not be easy to see for long. Comet brightness is determined several factors:
How close is it to the Sun The closer the comet is to the Sun, the hotter it will be and the more gases and dust will be released from the surface of the comet making the tail bigger and more reflective. The comet was closest to the Sun on July 3, and so should be starting to be dimmer and have a smaller tail each day that goes by.
How close it is to Earth The closer the comet is to Earth, the easier it is to see. The closer it is the larger it will appear in our sky and the longer the tail will appear. More light reflecting off the tail arrives in our telescopes, binoculars, cameras and eyes when it is closer. The comet makes its closest approach to Earth (103 million miles!) on July 22. So until that date, expect the comet to appear bigger and brighter each night.
How reflective the comet and tail are We don’t know the exact structure of the comet. The tail is made up of dust and ice from the surface of the comet. It is entirely possible that an outer layer could burn off and exhaust a large amount of dust and ice into the tail. It is equally possible that the surface could cool and become hard and the tail could dissipate quickly. This is the big unknown in predicting a comet. It might get brighter or dimmer all of the sudden. So appreciate it now before it goes away.
The solar wind This is a more minor factor, but the solar wind interacts with the tail of the comet. If there were a solar storm or a bout of turbulence in the solar wind it could speed the dispersal of the gasses in the tail. This is unlikely as we are currently in solar minimum.
After accounting for each of those factors, astronomers predicted NEOWISE to potentially be just visible to an unaided eye (magnitude 5-7). Reports are already coming in that is has a magnitude of around 1-2 (the smaller magnitude the brighter it is in the sky). It is possible that as it approaches Earth it could become one of the brightest and most obvious objects in the evening sky. Or… It could also wink out tomorrow. So hurry out to see it.